Emergency response systems are known for providing a realiable means for placing an emergency call to a central station in the event of an emergency condition, or actuating an alarm at a remote receiving station upon an emergency event. Preferably, these systems are employed for the aid and comfort of elderly or infirm persons who, for their personal well-being, should have ready access to an emergency facility, should the need arise. Such systems include a help unit housed within a small case which can be carried or worn by a user and which includes a button operative, upon actuation, to cause the transmission of a coded signal to a receiver disposed at the user's premises. Upon receipt of a transmitted help signal from the help unit, a visual and/or audible indication is provided that an emergency signal will be sent if the system is not reset within a short interval by the user. If the system is reset, the indicators are deactivated, and no emergency signal is sent. If, however, the system is not reset during the defined interval, an emergency signal is transmitted to the remote receiving station.
The help unit is battery operated, and a spent or underpowered battery could impair or prevent proper transmission of an emergency help signal with possibly serious consequences to a user in distress. It would be extremely beneficial to provide for the automatic detection of a low battery condition for the battery in the help unit and the signification of this condition directly to the user so that corrective action can promptly be taken by the user to replace the worn battery. In known emergency response systems in which a help call is placed via an automatically dialled telephone to a remote center, a low battery condition signified by low battery data in the transmitted help unit signal can be sensed at the remote center so that personnel at the center can later advise a user to replace the battery. The user in this type of system is not directly warned of a low battery condition, but is dependent upon notification of such condition by another person from the response center.